1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive employing data averaging techniques during retry operations to facilitate data recovery.
2. Description of the Prior Art
Disk drives typically employ an error recovery procedure for recovering an errant data sector when an error occurs during a read operation. If the anomaly which caused the read error is transient, the data sector may be successfully recovered by rereading the data sector during a retry operation. Otherwise if the anomaly is static, the data sector may be recovered by varying selected parameters in the disk drive during the retry operation. For example, U.S. Pat. No. 6,188,538 discloses a disk drive which induces an offset into the servo tracking algorithm during the retry operation in order to improve the likelihood of recovering an errant data sector. In another example, U.S. Pat. No. 5,721,816 discloses a disk drive which adapts parameters of a read channel, such as equalizer coefficients, during retry operations. In yet another example, U.S. Pat. No. 6,009,549 discloses a disk drive comprising a raw samples buffer for buffering the samples of the read signal in memory. During retry operations, the read signal samples buffered in memory are processed in multiple passes while adjusting various read channel parameters which overcomes the rotational latency of the disk. However, further enhancing the retry operation improves the likelihood of recovering an errant data sector.
There is, therefore, a need to improve the retry operation of a disk drive in order to further improve the likelihood of recovering errant data sectors.